Humans to blame for demise of gigantic ancient mammals

Though climate change patterns during this time period likely exacerbated humankind's negative influence on ancient mammalian populations, they were a lesser driver.

New research suggests human activity, not climate change, killed megafauna species like the woolly mammoth. Photo by AuntSpray/ShutterStock

EXETER, England, Aug. 13 (UPI) -- For many years, scientists have been trying to figure who or what killed the world's largest mammals -- like a giant game of Clue.

Previous research has suggested climate change was to blame. But a new study out of the University of Exeter puts the blame on humans, with their migrations and insatiable appetite for natural resources.

Researchers arrived at their conclusion after running a series of computer models analyzing the movement of ancient human populations and the disappearance of the world's megafauna, the largest mammals ever to roam the earth -- the sabertooth tiger, the woolly mammoth, the woolly rhino and the giant armadillo.

The timing of humans' arrival on new continents and the demise of massive mammalian species turned out to be too coincidental to ignore. The statistical analysis pointed to humans as the main driver of these ancient extinctions.

The disappearance of Earth's megafauna took place over the course of 80,000 years. All the largest mammalian species were gone prior to 10,000 years ago. Though climate change patterns during this time period likely exacerbated humankind's negative influence on ancient mammalian populations, they were a lesser driver.

"As far as we are concerned, this research is the nail in the coffin of this 50-year debate -- humans were the dominant cause of the extinction of megafauna," Lewis Bartlett, a researcher at Exeter's Center for Ecology and Conservation, said in a press release.

Unfortunately, researchers can't yet say what it was about the presence of humans that precipitated the decline of large mammalian species.

"What we don't know is what it was about these early settlers that caused this demise. Were they killing them for food, was it early use of fire or were they driven out of their habitats?" Bartlett said. "Our analysis doesn't differentiate, but we can say that it was caused by human activity more than by climate change. It debunks the myth of early humans living in harmony with nature."

The statistical analysis also can't sort out mammalian disappearance in Asia. Neither climate change nor mankind seem to be the strongest drivers of ancient extinctions on the continent.

"Whilst our models explain very well the timing and extent of extinctions for most of the world, mainland Asia remains a mystery," said Andrea Manica, Cambridge University researcher and author of a new paper on the subject -- published in the journal Ecography.

"According to the fossil record, that region suffered very low rates of extinctions. Understanding why megafauna in mainland Asia is so resilient is the next big question."